This research program on the protozoan parasite E. histolytica has focused on the isolation and characterization of surface antigens of amebae that interact with host intestinal cells, on understanding the immune response to E. histolytical infection, and developing recombinant antigen-based vaccines to prevent amebic disease. Many of these studies have utilized the serine rich E. histolytica protein (SREHP), a novel surface protein of amebae. The recent development of a scid mouse model of amebic infection, and the cloning and expression of 3 recombinant E. histolytica antigens to study protective immunity to amebic infection, and to develop vaccines to prevent amebic infection.